W. D. Carr—On the Lincoin Lias. 165 
absent or only very feebly represented. The following is a descrip- 
tion of the beds. Zone of :— 
( Ammonites bifrons. Light blue paper shales: few fossils. 
A. communis. Nucula Hammeri Beds. Blue Clay with septaria: many 
& fossils in bands. 
7 4 a. Blue clay with large septaria, gritty bands locally 
3 | passing into limestone: Belemnites very abundant. 
= | A. serpentinus. 
b. Blue pyritous clay with strong limestone bands weather- 
ing yellow. 
o 
Sa ) A. magaritatus. Slightly sandy shales with bands of ferruginous nodules : 
= few fossils. 
a 
= 2 ( A. capricornus. Thickly bedded hard blue shales with Ostrea bands (2) and 
= iS} /) small septaria. 
Just outside the city on the north cliff we find in the brick-pit 
belonging to Swan Brothers about 60 feet of the Upper Lias with 
the ironstone series of the Northampton Sand cropping out above it. 
Commencing at the top, and working downwards, we find beneath _ 
the ironstone about 31 feet of lightish blue shale, which splits up on 
the weathered surface into very thin lamine. ‘These beds contains 
few fossils, chiefly Ammonites bifrons in a fragmentary condition, and 
a few Belemnites. They terminate downwards in a thin band of 
septaria, below which come in the Communis Beds. On the top of 
the latter, and underlying the nodule band, is a bed of gritty dark 
coloured shale about 18 in. thick, made up largely of shelly debris, 
and containing Nucula Hammeri very abundantly. This bed is 
especially interesting as being the chief repository of the very rare 
Trigonia pulchella (rare at least in England, though known from 38 or 
A localities on the Continent), which in fact occurs only in this band 
and a few feet below it. Underlying this gritty band of shale 
we have clay 4 ft., and beneath that another gritty band 92 in. 
thick, similar to the first, and containing the same fossils. Again, 
below this comes clay 2ft. 6in., which terminates the Communis Beds, 
and brings us to the zone of Ammonites serpentinus. At the top of 
the Serpentinus beds we have a strong band of septaria, underlying 
which and filling the spaces between the nodules occurs another 
dark gritty shale, locally indurated into limestones very similar in 
appearance to those that occur in the Communis beds, but containing 
different fossils, minute species of Dentalium, Chemnitzia, and 
Acteonina occurring in hundreds, while fine examples of Belemnites 
subtenuis 5 or 6 inches long are abundant; very large examples of 
Ammonites serpentinus, and A. heterophyllus also occur, and a large 
Nautilus. Nucula Hammeri occurs very sparingly, and Amberlya, 
Delphinula and Astarte not at all. We have again blue shale 
for 12 inches below this, and then another band of gritty shale 
A inches thick, which contains the same fossils as the band 1 foot 
above it. Blue shale again follows for 8 inches, when we encounter 
a strong double band of septaria 2 ft. in thickness, and below it 
8 ft. of blue shale to bottom of pit. The whole of the beds in this 
pit are conformable and have a dip of about 4° HE. 30° N. 
